The present invention relates generally to aircraft deicing systems, and, more particularly, to deicers for use in helicopters.
The problems relating to the formation of ice on aircraft are well known, and date from the early days of aviation. In certain climatic conditions, ice has a tendency to form, especially in the vicinity of the leading edges of airfoil surfaces, in sheets of substantial thickness. The ice not only increases the effective weight of the aircraft, but it can also increase drag resistance and reduce the lift provided by the airfoil.
Various techniques have been employed in the past in an attempt to avoid the problem of aircraft icing. Early deicing devices were mechanical, some employing an inflatable cover or boot to crack the ice layer. Other prior art deicers employ electric resistance heating elements buried beneath the airfoil surfaces. The principal problem with these is that they heat a large section of airfoil surface, whether covered with ice or not. Since the surface is typically a metal and a good conductor of heat, deicers employing resistance heating are extremely inefficient, use a large amount of electrical power, and are typically heavy and quite costly. Moreover, the heating elements are not conveniently replaceable in the event of wear or damage.
Helicopters are, of course, just as prone to icing problems as fixed-wing aircraft. In fact, helicopters are probably more likely to be used in icing conditions than are fixed-wing aircraft. In addition, there is a practical difficulty in supplying deicing power to a rotating surface, rather than to one which is fixed relative to the body of the aircraft. Because of the aforementioned problems of inefficiency, high power and weight requirements, and unreliability of electric resistance deicing devices, until now there has been no satisfactory deicing system for helicopter use.
It will be apparent from the foregoing that there is a clear need for a deicing technique which avoids or minimizes the disadvantages of the prior art, and which is particularly useful for helicopter use. The present invention fulfills this need.